Hydrogen has long been considered an ideal fuel source, as it offers a clean, non-polluting alternative to fossil fuels. One source of hydrogen is the splitting of water into hydrogen (H2) and oxygen (O2), as depicted in equation (1).2H2O→O2+2H2  (1)
In an electrochemical half-cell, the water-splitting reaction comprises two half-reactions:2H2O→O2+4H++4e−  (2)2H++2e−→H2  (3)and hydrogen made from water using sunlight prospectively offers an abundant, renewable, clean energy source. As such, efforts have been made to search for efficient oxygen evolution reaction (OER) catalysts that can produce hydrogen from water. In particular, oxides of ruthenium and iridium have previously been identified. However, as they are among the rarest elements on earth, it is not practical to use these catalysts on a large scale. Therefore, an improved OER catalysts would be very useful in the development of hydrogen as an alternative fuel source.